The preferred embodiments of the present invention generally relate to electrical connectors for use with high speed serial data, and more particularly, to connector assemblies for transferring high speed serial data from a cable to a circuit board.
In the past, electrical cable assemblies have been proposed for connecting electrical cable to circuit boards. Conventional cable assemblies have been provided with an equalizer circuit board within the connector for performing signal conditioning. Performing signal conditioning within a circuit in the connector assembly, reduces the time required to incorporate signal conditioning circuit elements with a cable assembly and reduces the time required for connection of the circuit elements with the electrical contacts and the cable conductors. One example of a conventional cable assembly with an equalizer board is described in U.S. Pat. No. 5,766,027, commonly owned with the present application.
Conventional high speed serial data connectors (HSSDC) comprise a plug and receptacle combination interconnected through contact fingers. The plug receives an insulated holder that, in turn, receives an equalizer card. The equalizer card includes signal conditioning circuitry.
HSSDC connectors form a grounding plane surrounding the adjoining surfaces of the receptacle and plug in order to afford electromagnetic interference (EMI) shielding around the contact fingers forming the high speed serial data connection between the plug and receptacle. In conventional HSSDC connectors, the grounding plane has been maintained by locating a plurality of grounding beams on the top, bottom and side walls of the receptacle and engaging the top, bottom and side surfaces of the plug. Conventional grounding beams are J-shaped integral extensions of the walls and are bent to project forward, upward and into the opening of the receptacle. The J-shaped ground beams are biased inward to maintain an electrical connection with the plug once inserted.
However, J-shaped grounding beams take up an operation region inside the receptacle between the receptacle and plug walls. The region thickness substantially equals the radius of the J-shaped portion of the grounding beam. Consequently, the height and width of the opening in the receptacle must be greater than the height and width of the plug by an amount at least equal to the curved radius of the grounding beams. When grounding beams are located above, below and on either side of the plug, they undesirably increase the height and width of the receptacle. Certain applications for HSSDC connectors have significant space constraints.
In addition, the distance between the grounding beams should be maintained less than a predetermined maximum spacing. Otherwise, energy due to high speed signals radiates from the connection of the plug and receptacle. The spacing between grounding beams controls the frequency range at which signals may be carried through the connection. As the frequency of the transmitted signal increases, the maximum acceptable distance between the grounding beams decreases. The maximum distance is calculated between the two grounding beams that are furthest from one another (e.g., top to bottom, side to side, top to side or side to bottom). The connector assembly is preferably operable with frequencies having a wavelength range between six and twenty-four times greater than the largest distance between any two grounding beams.
The need for a large portion of the perimeter to be covered with grounding contacts is balanced with other design considerations, such as physical constraints, material cost, complexity and the forces needed to connect the plug and receptacle. As additional grounding beams or contacts are added, the plug becomes harder to insert into the receptacle since each contact presents a contact force to the plug that must be overcome to bend the contact open. A compromise is reached between the cost, complexity, physical size, forces needed to insert the plug and the EMI shielding characteristics of the connector.
Conventional HSSDC assemblies have used sheet metal to construct the plug and receptacle. Sheet metal is folded into a desired configuration. When protrusions, shelves and other features are desired to be added to the plug, holes must be punched through the sheet metal shell, or separate components must be fitted in the sheet metal to offer the features. Components, separate and apart from the metal shell, are also provided to latch the plug in the receptacle. It is undesirable to punch holes through the metal shell since the openings permit leakage of electromagnetic radiation. Conventional HSSDC connectors provide a plastic insert into the plug metal shell. The plastic insert includes the desired features for holding the PC equalizing board.
A need exists for an improved HSSDC connection assembly that simplifies the number of parts needed to construct the connector and reduces the physical dimensions of the connector without sacrificing electrical performance, latching performance or connection forces. It is an object of the preferred embodiments of the present invention to meet one or more of these needs and other objectives that will become apparent from the description and drawings set forth below.
In accordance with at least one preferred embodiment of the present invention, an electrical connector is provided having a conductive receptacle assembly with walls defining a connector opening. At least one of the walls includes grounding contacts. The electrical connector further includes a conductive plug member for connection to the receptacle assembly through the connector opening. The plug member includes peripheral surfaces that are electrically engaged by the ground contacts on the walls of the receptacle assembly. A latch assembly is mounted to the plug member. The latch assembly includes a spring bias facing plate that lockably engages one of the side walls of the receptacle when the plug is inserted into the receptacle. The latch assembly is conductive and maintains a grounding connection between the plug member and a wall of the receptacle to which the latch is secured. The grounding contacts maintain grounding connections between the remaining walls of the receptacle and the walls of the plug member in order that the latch assembly and grounding contact form a grounding plane that surround the periphery of the plug.
In accordance with one embodiment, the latch assembly includes a principal body extending laterally to be formed integrally with side flanges. The principal body extends in a longitudinal direction to be formed integral with the facing plate. A locking projection is formed on the facing plate and arranged to align with and directly engage a hole in the receptacle assembly. The facing plate remains bias against the receptacle assembly to maintain the latch and grounding connections. The latch assembly further includes a leading section having a hole and lower lip portion directly engaging a knob and a U-shaped recess in a front face of the plug member. The leading section of the latch is sandwiched between a front face of the upper shell and a cross bar of the lower shell of the plug member when the shells are combined.
In one embodiment, the latch assembly is comprised of a T-shaped body integrally molded with side flanges, the facing plate and a leading edge. The side flanges and leading edge include holes that snapably engage knobs projecting from the exterior of the plug member. The holes and knobs secure the latch assembly to the plug member.
In another embodiment, the receptacle includes multiple J-shaped ground beams provided along at least one wall of the receptacle proximate the opening thereto through which the plug is received. The J-shaped grounding beams are formed integral with lead edges of the walls of the receptacle and extend forward, upward and into the receptacle opening to form grounding connections with the plug.
In yet another embodiment, an electrical connector is provided having a plug assembly matingly connected with a receptacle for carrying high speed serial data from a serial cable. The connector includes an upper shell having a top, sides, a back end and front face all formed integrally with one another. A lower shell is provided with a bottom, sides, a back end and a front face all formed integrally with one another. The upper and lower shells sealably join one another along mating edges of the sides, back ends and front faces to form an EMI shielded chamber therein. A PC equalization board having signal conditioning circuitry is enclosed within the upper and lower shells. The PC equalization board includes side edges having a contour that conforms to an interior contour of the side walls. The PC equalization board directly contacts and is supported by the interior surfaces of the side walls of the upper and lower shells to maintain the PC board in a desired horizontal and vertical orientation and relation to the plug. The mating edges of the sides, front face and back end of the lower shell include a skirt. Corresponding edges of the sides, front face and back end of the upper shell include a recess configured to mate with the skirt on the lower shell in order to provide an EMI shielded connection therebetween.
In one embodiment of the plug, the front face of the upper shell includes pens extending forward therefrom. The front face of the lower shell includes a cross bar connecting the sides thereof. The pins on the upper shell are inserted under the crossbar of the lower shell to retain the front faces of the upper and lower shells securely engaged with one another.
In another embodiment of the plug, the back ends of the upper and lower shells includes integral upper and lower tubular sections, respectively. When the upper and lower shells are combined, the upper and lower tubular sections mate with one another to form a circular opening to receive the cable. A ferrule is inserted over the upper and lower tubular sections and crimped thereon to secure the back ends of the shells to one another.
In another embodiment of the plug, the interior surfaces of the lower shell include integral protrusions defining shells directly support the PC equalization board in a desired vertical position and orientation. The interior surfaces of the lower shell also include integral protrusions defining keys that are received within recesses in either side of the PC board to maintain the PC board in a desired horizontal position and orientation with respect to the plug.
In yet another embodiment of the plug, the bottom of the shell is provided with a notch, while the receptacle is provided with a polarizing key. The notch and polarizing key are configured to align with one another only when the plug is properly oriented relative to the receptacle. The plug may not be inserted into the receptacle until the polarizing key is aligned with a notch, thereby preventing incorrect connection.
In one embodiment, the upper and lower shells are formed of diecast injection molded conductive material.